Detect Sound Direction

Our ears let us know approximately which direction sounds are coming from.
Some sounds, like echoes, are not always informative, and there is a mechanism for
filtering them out.

A major purpose of audition is telling where things are. There’s an analogy used by
auditory neuroscientists that gives a good impression of just how hard a job this is. The
information bottleneck for the visual system is the ganglion cells that connect the eyes to
the brain [Understand Visual Processing]. There are about a million in each eye, so, in your vision, there are about
two million channels of information available to determine where something is. In contrast,
the bottleneck in hearing involves just two channels: one eardrum in each ear. Trying to
locate sounds using the vibrations reaching the ears is like trying to say how many boats
are out on a lake and where they are, just by looking at the ripples in two channels cut out
from the edge of the lake. It’s pretty difficult stuff.